Asphalt drying, heating, and mixing plant.



C. E. GUELIGH.

ASPHALT DRYING, HEATING, AND MIXING PLANT.

APPLICATION FILED OCT. 24. I911.

RENEWED DEC. 30,19l5.

Patented July 11, 1916.

8 SHEETS-SHEET I.

C. E. GUELICH. ASPHALT DRYI NG, HEATING, AND MIXING PLANT. APPLICATION FILED OCT. 24. 1911.

RENEWED DEC. 30,1915.

Patented July 11, 1916.

8 SHEETS-SHEET Z.

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ASPHALT DRYING, HEATING, AND MIXING PLANT. APPLICATION FILED OCT. 24.. I911- RENEWED DEC. 30. I915- Patented July'll, 1916.

8 SHEETS-SHEET 3' wwm.

MzT/M C. E. GUELIGH.

ASPHALT DRYING, HEATING, AND MIXING PLANT. APPLICATION FILED OCT. 24, I9II- RENEWED DEC. 30,1915 1L 1L 9I %Q, Patent-ed July 11, 1916.

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ASPHALT DRYING, HEATING, AND MlXING PLANT.

RENEWED DEC. 30.1915.

APPLICATION FILED 0CT.Z4,19H.

Patented July 11, 1916.

mmm n 8 SHEETS SHEET 5 C. E. GUELICH.

ASPHALT DRYING, HEATING, AND MIXING PLANT.

APPLICATION FILED ocTv 24. I911- RENEWED DEC. 30.1915.

1 11, flfii n Pafented July 11, 1916.

8, SHEETS-SHEET 6.

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C. E. GUELICH. ASPHALT DRYING, HEATING, AND MIXING PLANT. APPLICATION FILED OCT. 24. I911.

RENEWED DEC. 30,1915.

Patented July 11, 1916.

8 SHEETS-SHEET 7.

iwi/macaw C. E. GUELICH.

ASPHALT DRYING, HEATING, AND MIXING PLANT. APPLICATION FILED OCT- 24' I911- RENEWED DEC. 30| 1915.

I I II Patented July 11, 1916.

8 SHEETS-SHEET 8- 5 mm nto c M CHARLES E. GUELICH, 01E KINGSTON, PENNSYLVANIA, ASSIGNOR TO GUELIOH PAVING PROCESS COMPANY, OF HURON, SOUTH DAKOTA, A CORPORATION OF SOUTH DAKOTA.

ASPHALT DRYING, HEATING, AND MIXING PLANT.

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Specification of Letters Patent.

Patented July til, 11916.

Application filed October 24, 1911, Serial No. 656,490. Renewed December 30, 1915. Serial No. 69,504.

To all whom it may concern:

Be it known that I, QHARLEs E. Gunmen, a citizen of the United States, and a resldent of Kingston, in the county ofInizerne and State of Pennsylvania, have lnvented certain new and useful Improvements in Asphalt Drying, Heating, and Mixlng Plants, of which the following is a speclficatlon.

This invention relates to improvements in asphalt drying, heating and mixing plants, and it especially relates to portable plants for pavingand other purposes. I

-While the invention is particularly adapted to the production of asphalt mixture, it is, of course, not restricted to cases 1n which asphalt or its products is used, but can be employed in the productions of many prod nets of concrete or other plastic material, m which drying a'nd mixing of the ingredients are required.

A continuous asphalt drying, heatmg and mixing plant, broadly considered, requires the following elements among others a drier to dry the aggregates before delivery to the mixer; a mixer and cooker to thoroughly mix, cook and incorporate the dried aggregates with the molten asphalt; de vices for automatically conveying the dried aggregates to said mixer; devices for supplying proper quantities of themolten asphalt to the aggregates in the mixer; and

controllable motor agencies for imparting the proper motions to the mixer, the drier, the conveyer and other parts of the apparatus in harmonious relation. If the apparatus is portable, then the installation should also include devices'by which the motor can be made to drive the vehicle upon which the apparatus is mounted.

It is the aim of the present invention to render the operation strictly and automatically continuous; to greatly increase the output of the installation; diminish the liability of clogging the mixer, driers or conveyers; and place the whole more perfectly under control of the operator.

To these ends the invention, among other important points, relates to a mixer and cooker consisting of a rotary chamber arranged to be practically closed during the operation of mixing and cooking, whereby such chemical changes are produced in the asphalt and the aggregates, one or both, that the asphalt actually impregnates the particles of aggregates. Whereas in the art as heretofore practised the particles of the aggregates have been coated with the asphalt, in my invention the particles of the aggregates are actually penetrated throughout and impregnated by the asphalt, and a far superior mix for paving and other purposes is thereby obtained.

The invention further relates to the operative combination with a mixer and cooker of a plurality of driers, since I have found that in the operation of such plants this produces a very great increase in the output.

The invention further includes the combination with the mixer and the driers of a circumferential elevator-conveyer, arranged so that a single-elevator conveyer having a continuous motion will serve all the driers. In this respect my invention has a capacity and operates with a simplicity of construction exceeding what has ever before been accomplished in this class of apparatus.

The invention further includes the construction of the mixer, whereby proper motions of the mixer and its devices are attained, and the smoothest possible interior is produced; the liability of material sticking to and burning on, and gradually clogging the mixer being reduced to a minimum, and the regularity and success of the mixing operation being promoted.

The invention also relates to the construction of the driers, and the means for imparting the proper motions to the driers.

The invention also relates to the circumferential elevator-conveyer, and its operative connections with the driers and the mixer, as will be hereinafter more fully set forth.

The invention also relates to the worm feed and associated parts, whereby the dried aggregates and the molten asphalt are fed in suitable regulated quantities to the mixer.

The invention also relates to the Various controlling devices, whereby in case of need, the several parts may be independently started or stopped.

The invention also relates to the devices for propelling and for controlling the pro pulsion of the truck on which the apparatus is mounted.

The invention also relates to other parts, and combinations, as will be apparent from the description and the claims hereinafter contained.

Referring to the drawings which accompany the specification, to aid the description, Figure 1, (Sheet 1) is an elevation of the rear, or supply,end of the machine. Fig. 2, (Sheet 2) is an elevation of the front, or conveyer, end thereof. Fig. 3, (Sheet 3) is a longitudinal vertical section of a drier andcertain other parts, and of certain gearing. In this view, also, the mixer, fuel oil tank and other parts are shown in elevation. Fig. 4, (Sheet 1) is a cross section of a drier. Fig. 5, (Sheet 4:) is a vertical longitudinal section, on a large scale, of the mixer and its hopper, and showing the worm feed and mixing blades in elevation. Fig. 6, (Sheet 4) is an end view of the mixer, With a head removed, and showing the mixing blades. Fig. 7, (Sheet 4:)

. is a detail of the mixing drum and the housgitudinal vertical section, as on the line 10-10 of Fig. .11, and on large scale, of the worm feed and easing therefor, and showingthe chambers both for the aggregates and for the asphalt; Fig. 11, (Sheet 2) being an elevation looking at the left end of said casing. Fig. 12, (Sheet 6) is a transverse vertical section of the fire box, the fire brick being however shown only in one compartment, for simplicity of representation. Fig. 13, (Sheet 6) is a side elevation of the fire-box. Fig. 14, (Sheet 6) is a broken top view of the housing, indicating the smoke stack, the flue, and controlling dampers therefor. Fig. 15, (Sheet 6) is a vertical cross section .of the base of the stack and the flue. Fig. 16, (Sheet'7) is a broken plan view on large scale, of the vehicle driving and steering gear. Fig. 17, (Sheet 1), is a sectional detail, on large scale, of mixer door. Fig. 18, (Sheet 8), is a broken longitudinal section and elevation of preferred construction of a shield for the mixer. Fig. 19, is a vertical cross section on the plane of the line 1919 of Fig. 18. Fig. 20 is a broken detail of said shield in elevation.

The housing and fire bow.Various parts of the apparatus are set in a sheet metal housing A, (Figs. 1, 2 and 3) suitably constructed with uprights and horizontal beams a, a on a truck B. The interior of said housing A is connected with and heated bythe furnace or fire-box F, (Figs. 12 and 13). On top of said housing A is a smoke stack S, the base of which communicates with a longitudinal flue f carried along inside the top of said housing and nearly to each end thereof. The ends of said flue f are open and communicate with the interior of said housing near the ends thereof,

so that a single flue serves to produce a proper movement and distribution of the products of combustion 'through said housing and toward both ends thereof; and said flue is controlled by dampers d, (Fig. 14) operated from the outside of the top. of the housing by handles and rods (l. Said firebox F (Figs. 12 and 13) consists of a sheet metal casing or shell, preferably of the shape shown, properly suspended on the truck B below the said housing A, and preferably formed with two divisions or furnaces. Said divisions or furnaces are respectively connected by suitable openings with the interior of the housing. Said firebox contains perforated fire brick f, (Fig. 12), forming a longitudinal chamber with numerous lateral openings, and an oil burner B projects a flame under air or steam pressure into said fire brick, in the known manner, producing intense heat; the products of combustion ascending into said housing A, and heating the drier, the mixer, and the asphalt tanks. ably be a burner for each furnace, supplied with oil by pipe I), controlled by a valve from an oil tank T, mounted on top of said housing A, (Fig. 3). Said housing A may be constructed of any suitable materials. But I prefer to construct it of an outer and inner steel plate, respectively 1 and 2,

in Fig. 7, with a layer of asbestos fabric 3,

between the plates; for, by this construction, the housing is rendered an excellent nonconductor of heat. The mixer M and the driers D, D, or their heads, may require to pass through the housing wall, and I prefer to make the joints by placing annular flanges A and S on said heads, positioned to wipe against said outer steel plate 1 as the mixer, or the driers revolves, (Figs. 5 and 7).

The (liters-There are two similar driers, D, D each arranged to supply dried aggregates to the same mixer M, and adjacent to opposite sides thereof, (Fig. 1). Each said drier D consists of a shell 5, and placed at a suitable inclination with the horizontal, to effect the proper longitudinal feeding of the contents from the receiving to the delivering end, and fixed concentrically at the receiving end to a head 6, and at the opposite end to a spider 7, keyed on the shaft 9, by whichthe drier is rotated; said shaft 9 having a gear meshing with a gear train, whereby said shaft 9 is driven from the prime motor, as will be hereinafter more fully explained. Another spider 11, keyed on the end of said shaft 9, secures said shaft to said shell 5 in proper alinement. Longitudinal flanges or ribs 12, (Fig. 4), fixed to the inside of said shell 5, serve to thoroughly stir up and pitch about the aggregates. Said aggregates, consisting of a mixture of broken stone, sand, or of any other desired There will prefermaterials, having been suitably mixed to gether, are dumped into the hopper D, the throat D of which delivers through said head 6 into said drier D; said throat D be ing provided with a. circular flange 14 concentric to said head 6, and working in an annular concentric groove of said head, 15 being an annular flange plate positioning said flange 14 in said groove. The flange of said head 6 is supported on rollers 16, (Fig. 1). Said hopper D is fixed to the upper end of said throat D and the whole is rigidly supported on the housing floor by the bracket tation of said drier D causes the aggregates to feed gradually down grade toward the discharge end of the drier, the inclination and rotary speed being adjusted to subject said aggregates to the drying action for the proper time. Finally the dried aggregates are discharged from the drier and by the chuteD (Fig. 3), upon the elevator conveyer, by which said aggregates are conveyed to the proper chutes or hoppers, and delivered to the worm feed, whereby they are supplied regularly and in proper quantities to the mixer.

The elevator conveyer.-Said chute D delivers said aggregates through the boxing 18, which incloses the bottom and sides of '(which I shall from time to time hereinafter designate simply as the conveyer), is suitably guided'around chain wheels 22,

properly supported in bearings adjacent to the four corners of said housing A, so that said conveyer, as it were, passes around said housing. 1 indicate this arrangement by the term circumferential conveyer, or circumferential elevator conveyer, and it is an important part of my invention, since it enables a single conveyer to serve several driers and deliver the aggregates to several chutes, and with one continuous direct motion of the conveyer. The result is a greatly increased conveyer capacity, and in a strictly continuous operation. Said conveyer is conveniently driven by employing one of said chain wheels 22, or rather a pair of them on a single axle, as the driver, for

example the upper right hand pair in Fig.

2-; it being understood that all said wheels 22 are arranged in pairs fixed on short axles, so that one wheel guides and supports a chain or cable at each side of the conveyer. The shaft 23 is provided with a suitable pulley driven by an endless chain 24, which is in turn driven by a pulley fixed on a shaft 25, which has a similar fixed pulley driven in its turn by. chain 27, from pulley 28 on an The inclination and the roaxle 29, driven by suitable gearing from the prime motor and at the proper speed. The v aggregates having been delivered on the bottom of said boxing 18, the buckets of the conveyer, traveling practically in contact with said bottom, scrape up and push along said aggregates until the buckets turn right side up at the corner of the housing and ascend more or less full of the aggregates. As the buckets near the top of their travel they enter a boxing or casing 30, which extends across over the housing A and has a horizontal floor 31 extending from journal to journal of the upper wheels 22. As the buckets turn at the upper left hand wheel they dump the aggregates onto said floor 31, which is provided with two pivoted doors 33, each of which communicate with its respective compartment 34, or 35, of a chute 36 which delivers the aggregates into the worm feed casing W. The pivot rods 38 of said doors 33 are extended out through the boxing 30, with suitable arms on the outer ends connected by a hand lever so that the attendant by one lever can actuate both doors. Said doors are normally set so that when one is closed the other is open. The aggregates being )dumped upon the said floor 31, the tilted buckets traveling practically in contact with said floor push the aggregates along, and they fall, by whichever door 33 is open, into the proper compartment of said chute 36, andthence to the worm feed casing. Said compartments have sliding gates at the bottom opened and operated by the attendant. if it is desired, at any time, to discharge the aggregates into chute 40, both doors will be closed by disconnecting the operating levers, and the buckets will then push the aggregates into said chute 40, the valve which normally closes its upper end being now opened. The

buckets having emptied their contents upon said floor 31, turn downward at the upper right hand corner, at the said driving wheel, and descend again into the boxing 18, again traversing through said boxing, being filled, ascending, dumping their contents again on floor 31, and so on continually.

The worm feed.Each of said compartments 34, 35 ofv said chute 36 communicates at its lower end'with the hopper 'wof the worm feed casing -W, (Figs. 2' and 10). Said casing is provided with thelarger cylindrical chamber 41, within which is the Worm W on the Worm shaft 'w driven by suitable gearing from the prime motor; and also with-the asphalt passage 42 communicating with the lower end of a pipe 44, (Fig.

3), controlled by a valve 46, and leading from the asphalt measuring tank 47, in which themolten asphalt is placed from the asphalt tanks K, K. Said worm W-should be of substantially less diameter than said chamber 41, in order to prevent clogging in proper quantities, into the mixer; the inner end of. the said worm casing W being cut away, forming a lip 50 which effects the abrupt fall of the aggregates into the mixer I just before they begin to be mixed with the molten asphalt. A measured quantity of asphalt is put in said tank 4:7, and the attendant, by operating said valve 46, regulates the supply of the asphalt to the mixer by the said channel 42, so that the asphalt and the aggregates drop practically together into the mixer M without danger of clogging the worm.

The mt'wer.Said mixer M consists of a cylindrical metal shell set eccentrically be- I tweentwo heads M M (Fig. 5). shell has opposite eccentricity, with respect trically on a horizontal line with each other,

The

to the two heads, which are set concenso that the mixer as it rotates, acquires a rolling and tumbling motion. Said mixer shellismade as smooth as possible on the inside; great care being taken that rivet "heads shall be sunk flush, seams carefully butted,'andthe like, so that said shell shall not catch up the contents, as a rough shell would. This is a valuable feature of my apparatus,- for it materially diminishes the sticking "of the contents to, and their burn- .ing on the shell, and the gradual impairment'of' operation, and clogging of the shell. The'said heads M ,.M are each flanged, and part of the flange of head M is provided 1 s with gear teeth meshing with and driven by gear. 98, which is in turn driven from the primemotor. The flange of said head M is supported onrolls 58, and the untoothed part .of the flange of head M is supported on rolls 59, (Figs. 1 and 5). Transverse bladesP, P extending partly across the interior of'the shell, are secured in position by beingfastened transversely to rods 52, which extend fromendfto end of the shell, being fastened to said heads M M by angles as indicated; and said blades P, P are turned at such an angle to the axis of the shell that,

i as the shell rotates and tumbles, said blades serve'both for mixing the contents and for propelling them longitudinally toward the discharge end of the mixer. And I find that'the worm feed, the rotation and tumbling of the shell, and the. efi'ect of the inclined blades produce a regular movement of the contents from the inlet to the discharge end of said mixer; the rotary speed and the propelling action being such, as to subject the contents of the mixer to the mixing action for the proper time. The discharge head M of said mixer is provided with a hinged door M (Figs. 1 and 17), equipped with a pivoted spring latch 54, which normally holds said door M closed. But the attendant by striking said latch with a hammer shifts it so that the door can open as the mixer revolves, the door then swingingfull open and being caught by the catch 55, and held open until released by the attendant. Now, when the mixer revolves to such position that'the door opening is lowermost, the contents of the mixer discharge by the chute 56, to carts or to any other receptacle. A suitable clutch hereinafter more precisely referred to enables the attendant to stop the mixer, Whenever he wishes, Without stopping other parts of the apparatus; and other suitable clutches proyide for independently stopping and starting the worm feed and other parts of the apparatus. I prefer to provide a small orifice 57, covered by a movable flap 57 in the center of said head M (Fig. 2) for escape of Vapor, inspection and other purposes. During the operation of cooking and mlxlng, said mixer M is closed practically tight, because, at the inlet end, the aggregates fill and close the chamber 41 as they are pushed and more or less compressed by the worm W, and the asphalt fills and closes the channel 42, and because at the outlet end, the dust and condensable vapors'fo'rm a practically gas tight packing around the lip of said door M and said flap 57 will be normally closed. In the said closed mixer the temperatures and gaseous pressures become relatively high, with chemical changes in the asphalt and rock of the aggregates,

which is preferably a lime stone, and the asphalt, as hereinbefore stated, thoroughly penetrates and, impregnates particles of stone. My closed mixer also greatly improves and rejuvenates inferior or old asphalt, by employing proper oil mixtures,

and sald closed mlxer is an important element of my invention.

I prefer to place a deflecting shield around the lower part of the mixer M, to permit of cutting off the heat from said mixer in case it is desired to use or heat only the driers. This shield is however, not indispensable and is illustrated only in Figs. 18, 19 and 20, wherein it is shown constructed of curved metal plates I, I, with a layer of asbestos J between, properly stiffened by ribs H and suspended from rods k, h. Said shield is provided with openings y protected by slides a: operated from outside said housing A by suitable rods and handles. When said slides a: are opened the hot products of combustion pass through said opening :1 and heat said mixer. When said slides are closed the mixer is cut off from the heat, and the driers I output and render the operation absolutely continuous by employing two asphalt tanks,

' K, K, indicated in Fig. 1, each arranged for frames. of the housing A, with their bodies projecting downwardly into the aforesaid flame chamber of said housing A, so that .the same flame which heats the driers and the mixer melts the asphalt. Thus a single oil burner, or a pair of burners, if there are two furnaces, serves for the several purposes of drying the aggregates, heating the mixture of aggregates and asphalt, and melting the asphalt, and this is an important feature of my invention. Each of said tanks has a cover 60, provided with a strong hinged lid 61, to permit of filling the tank with the asphalt, and also to permit the drawing off of the molten asphalt from the tank into the aforesaid measuring hopper 47. During the melting of the asphalt, said lids 61 will be closed, except when, from time to time as necessary, one is opened to ladle out the molten material into said hopper 47 and I prefer to take asphalt from said tanks alternately, wherebyone tank is always full and hot, during: a job. A suitable piunp may be employed to pump the molten asphalt from the tanks K to the measuring hopper 47.

The motor tm07c.-l[ prefer to mount my apparatus on a motor-truck, deriving the power to run the truck from the same prime mover as drives the various parts of the apparatus. A gear 80, (F ig.-16) loose on shaft 71 meshes with a gear 72, (Fig. 8) which is, in turn, driven by gg ar'73 on engine shaft E. A clutch 75, lg. 16) operated by'theengineer, through suitable clutch lever, serves to connect and disconnect said gear with and from said shaft 71. A beveled pinion 76 on said shaft 71 meshing with a beveled gear 77 fixed on a counter shaft 78 drives said shaft 78 and chain wheels 79 fixed thereon, and endless chains 80 from said Wheels 7 9 drive large chain wheels 81 adjacent to the truck Wheels 83 fixed on the truck wheel shaft 82; and thereby the truck is propelled as desired.

To steer the truck, the rear wheels and adjacent parts of the truck are constructed and arranged as follows: ()n the under side of the truck frame 80, equidistant from and at opposite sides of the king bolt 87, are secured circular segments 88, (Fig. 16), which rest on rollers 84 carried in stout uprights on the bolster 85 of the rear axle 86. Said king bolt 87 passes down through a plate, which is fixed to said truck frame, into the said axle bolster 85, (Figs. 1 and 3). Said bolster 85 is provided with a toothed segment 90, meshing with a worm 91, on the axle of which is fixed a gear 92,

meshing with a pinion 93 fixed on a horizontal transverse shaft 94 turning in bearings in the truck frame and having a hand wheel 95 on the outside of the truck, which can be readily operated by a man running or walking alongside of said truck as it travels. Thus a man on the road can readily steer the machine in any desired direction.

The prime motor and gearing.An important, but not an essential feature of my invention, is the combination and arrangement of parts by which a single prime motor supplies all the motive power, both for working the apparatus and for propelling the truck. I prefer to employ a steam boiler with oil fuel or a gas engine, but of course any suitable type of boiler and engine might be used. On the main engine shaft E, (Figs. 3 and 9) is said gear 73 meshing with said gear 72; and that meshing both with aforesaid wagon gear 7 O and with gear 96 which drives said shaft of said worm feed W. Said gear 72 has a clutch 114 for driving shaft 97 which has at its other end gear 98, which drives the gear on the head M of said mixing drum, (Figs. 5, 8 and 9). A small gear on said shaft 97 meshes with two similar gears 99 respectively on the counter shafts 100,.and small gears 101, on said shafts 100 mesli with large gears 102 fixed on and driving the said shafts 9, 9 of the respective driers.

The clutches-Said gear 96, loose on the said worm feed shaft to is connected with one member of clutch 110, the other member of which is fixed on said shaft 'w Thus by throwing said clutch on or oif, said worm feed is stopped or started independently of the mixer. Said gear 98 is loose on shaft 97, and connected by a sleeve with one member of a clutch 112, (Fig. 9). The other member of said clutch is secured to said shaft 97. Thus by throwing said clutch 112 on or ofi, the mixer can be started or stopped independently of other parts of the apparatus. Said gear 72 is loose on said shaft 97 and connected with one member of the main clutch 114, the other member of which is fixed on said shaft 97. Thus by throwing said clutch 114 on or off, the apparatus generally may be started or stopped; and while said clutch- 114 is on, the said other clutches 7 5, 110, 112 provide for independently stopping or starting the truck, the worm feed and the mixer, and the several clutches give the attendants complete control over the several parts of the machine. The aforesaid clutches may be of any suitable kind, and I prefer to use friction clutches provided with springs acting to draw the members of the clutch into operative connection. Clutch 114 may however-be of the toothed variety.

Now having described my improvements, 1 claim as my invention.

1. The combination in apparatus of the v closure for said compartments whereby each kind specified, of a mixer and a plurality of driers, a conveyer in operative communication with each said drier, a plurality of compartments for dried material in operat1ve connectlon with sa1d mixer, and a said compartment may independently receive dried material from said conveyer.

2. The combination in apparatus of the kind specified, of a mixer, a plurality of driers adapted to supply dried aggregates for said mixer, a chute provided with a plurality of compartments, one for each said drier, and all said compartments being operatively connected with said mixer, means to close the inlet of one or the other said compartment, and a conveyor adapted to convey dried aggregates from one or the other drier to one of said compartments,

whereby either of said driers may be Operated singly.

3. In, apparatus of the kind specified, the

v combination with a rotary mlxer of a wormmeans to deliver dried aggregates from either drier to sa1d mixer, and means to mix molten asphalt with said aggregates as they enter said mixer, and a circumferential conveyer adapted to convey the dried aggregates from each drier.

5. The combination in apparatus of the kind specified, of a rotary mixer, a plu rality of rotary driers in operative connection therewith, whereby one or the other of said driers may be inoperative without stopping the feed of materials to said mixer, and a Worm feed device operatively connected with said mixer, and provided with a channel for aggregates and with a separate channel for molten asphalt.

6. The combination in apparatus of the kind described, of a housing, a rotary mixer in said housing having a smooth shell, blades in said mixer supported independently of said shell and separated therefrom, a plurality of rotary driers in said housing, means for feeding material to said mixer, and an elevator conveyer adapted to convey dried material from all of said driers to said feeding means.

7. In apparatus of the kind specified, the combination with a mixer and a plurality of driers, of a plurality of compartments for feeding material to said mixer and means for closing the inlet of one or another of said compartments, and a conveyor adapted to convey material from said driers to one or the other of said compartments, whereby one or the other of said driers may be inoperative as desired.

Signed at Wilkes-Barre, in the county of Luzerne, and State of Pennsylvania, this 20th day of October, A. D. 1911.

Witnesses:

H. A. 'MINER, W. L. SPERoE. 

